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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

19803 results found.

  1. GRB 251122A / EP251122a: SVOM detection of a long burst
  2. EP251122a: Einstein Probe detection of an X-ray transient
  3. EP251118a: Continued Optical Detection with Kinder observations
  4. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  5. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  6. EP251118a: Xinglong-2.16m optical observation
  7. EP251118A: 1.3m DFOT optical afterglow detection
  8. GRB 251118A: Swift/UVOT Detection
  9. EP251118a / GRB 251118C: SAO RAS optical observations
  10. GRB 251118A: Swift-XRT afterglow detection
  11. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  12. EP251118a: Optical detection with Kinder observations
  13. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  14. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  15. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  16. EP251118A / GRB 251118C : MASTER optical counterpart observations
  17. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  18. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  19. EP251118a: VLT near-infrared observation
  20. GRB 251116D: SVOM/GRM observation of a long GRB
  21. GRB 251119A: SVOM detection of a possible burst
  22. EP251118a: NOT spectroscopic redshift of z = 1.216
  23. EP251118a: NOT candidate optical counterpart
  24. EP251118a: Einstein Probe detected of a fast X-ray transient
  25. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  26. GRB 251116C: SVOM/ECLAIRs refined analysis
  27. GRB 251116B: SVOM/ECLAIRs refined analysis
  28. GRB 251115A: Swift-XRT observations
  29. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  30. GRB 251117A: SVOM/GRM observation of a short burst
  31. GRB 251117A: Fermi-LAT detection
  32. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  33. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  34. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  35. EP251023a: Assy AZT-20 optical observations
  36. EP251023a: UAFO and AbAO optical observations
  37. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  38. GRB 251025B: further Mondy optical observations
  39. GRB 251111A: Mondy optical upper limit
  40. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  42. GRB 251116B: LCO optical upper limits
  43. GRB 251116C: LCO optical upper limits
  44. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  45. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  46. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  47. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  48. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  49. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  50. GRB 251113A: AstroSat CZTI detection
  51. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  52. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  53. The EP-WXT trigger 01709248221 is likely a flaring star
  54. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  55. GRB 251111A: SVOM/ECLAIRs refined analysis
  56. GRB 251025B: SVOM/ECLAIRs refined analysis
  57. GRB 251112A: Swift/UVOT Upper Limits
  58. GRB 251108C: AstroSat CZTI detection
  59. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  60. Swift Trigger 1413695: a possible GRB 251112A
  61. GRB251111A: 1.3m DFOT optical upper limit
  62. GRB 251111A: Swift-XRT afterglow detection
  63. GRB 251111A: SVOM/VT optical observations with X-band data
  64. GRB 251111A: SVOM/VT optical observations with VHF data
  65. GRB 251111A: LCO optical observation
  66. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  67. GRB 251106A: Swift/UVOT Upper Limits
  68. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  69. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  70. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  71. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  72. GRB 251102B: SVOM/GRM observation
  73. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  74. The EP-WXT trigger 01709248051 is likely a flaring star
  75. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  76. GRB 251106A: Swift-XRT afterglow detection
  77. GRB 251106A: Kilonova-Catcher optical upper limit
  78. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  79. GRB 251106A: MASTER optical observations
  80. GRB 251103B: AstroSat CZTI detection
  81. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  82. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  85. GRB 251103B: Swift/UVOT Upper Limits
  86. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  87. GRB 251103A: WFST optical observations
  88. GRB 251103A: OHP/T193 optical observations
  89. GRB 251103A: Xinglong 2.16m optical detection
  90. GRB 251103A: KAIT optical observations
  91. GRB 251103B: Nanshan/HMT optical upper limit
  92. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  93. GRB 251103B: MITSuME Akeno optical upper limits
  94. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  95. EP251102a: NIR observations with WINTER
  96. GRB 251103A: J-band detection with WINTER
  97. GRB 251103B: GROWTH-India Telescope optical upper limits
  98. GRB 251103A: Kilonova-Catcher optical afterglow detection
  99. GRB 251103B: Enhanced Swift-XRT position
  100. GRB 251103B: Swift detection of a burst

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